1. Field of the Invention
The present invention relates to a mounting structure of an ignition plug tube for encircling and protecting an ignition plug in an internal combustion engine.
2. Background of the Invention
A mounting structure of an ignition plug tube is disclosed in JP-A No. 2004-100651, for example. An ignition plug tube disclosed in this document is a cylindrical member. A lower end of the cylindrical member is inserted into a plughole formed in a cylinder head. A flange is formed in a position slightly lower than an open end face at an upper end thereof. The flange is fitted into a circular hole of a cylinder head cover for positioning. The leakage of oil is prevented by this arrangement.
As described above, when the flange is formed on the cylindrical member of the ignition plug tube, the cost of the ignition plug tube itself is greatly increased. When the ignition plug tube is made of a cylindrical member without the flange, the leakage of oil is prevented by press-fitting the sealing member into the cylinder head cover. However, a part for preventing the detachment of the sealing member itself is separately required and the number of parts increases.